Effect of multiple phosphorylation events on the transcription factors FKHR, FKHRLI and AFX

2002 ◽  
Vol 30 (4) ◽  
pp. 391-397 ◽  
Author(s):  
Y. L. Woods ◽  
G. Rena
Keyword(s):  
Transcription Factors ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Critical Role ◽  
Chromosome X ◽  
Kinase Cascade ◽  
Phosphoinositide 3 Kinase ◽  
Fused Gene ◽  
Pkb Phosphorylation

The insulin-stimulated phosphoinositide 3-kinase (PI 3-kinase)/3-phosphoinositide-dependent kinase-1 (PDK1)/protein kinase B (PKB) kinase cascade is believed to play a critical role in metabolic control and cell survival, largely mediated through PKB phosphorylation of many proteins. Recent findings demonstrate that the transcription factors FKHR (forkhead in rhabdomyosarcoma), AFX (ALL1 fused gene from chromosome X) and FKHRL1 (FKHR-like 1; termed FKHR isoforms) are phosphorylated by PKB in cells, leading to their exit from the nucleus. These exciting results suggest that FKHR isoforms may be critical effectors of PI 3-kinase/PDK1/PKB signalling in vivo.

scholarly journals Domain Swapping Used To Investigate the Mechanism of Protein Kinase B Regulation by 3-Phosphoinositide-Dependent Protein Kinase 1 and Ser473 Kinase

1999 ◽  
Vol 19 (7) ◽  
pp. 5061-5072 ◽  
Author(s):  
Mirjana Andjelković ◽  
Sauveur-Michel Maira ◽  
Peter Cron ◽  
Peter J. Parker ◽  
Brian A. Hemmings
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase B ◽  
Second Messengers ◽  
Activation Mechanism ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Phosphoinositide 3 Kinase ◽  
Regulatory Sites

ABSTRACT Protein kinase B (PKB or Akt), a downstream effector of phosphoinositide 3-kinase (PI 3-kinase), has been implicated in insulin signaling and cell survival. PKB is regulated by phosphorylation on Thr308 by 3-phosphoinositide-dependent protein kinase 1 (PDK1) and on Ser473 by an unidentified kinase. We have used chimeric molecules of PKB to define different steps in the activation mechanism. A chimera which allows inducible membrane translocation by lipid second messengers that activate in vivo protein kinase C and not PKB was created. Following membrane attachment, the PKB fusion protein was rapidly activated and phosphorylated at the two key regulatory sites, Ser473 and Thr308, in the absence of further cell stimulation. This finding indicated that both PDK1 and the Ser473 kinase may be localized at the membrane of unstimulated cells, which was confirmed for PDK1 by immunofluorescence studies. Significantly, PI 3-kinase inhibitors prevent the phosphorylation of both regulatory sites of the membrane-targeted PKB chimera. Furthermore, we show that PKB activated at the membrane was rapidly dephosphorylated following inhibition of PI 3-kinase, with Ser473 being a better substrate for protein phosphatase. Overall, the results demonstrate that PKB is stringently regulated by signaling pathways that control both phosphorylation/activation and dephosphorylation/inactivation of this pivotal protein kinase.

scholarly journals Protein Kinase B Activation and Lamellipodium Formation Are Independent Phosphoinositide 3-Kinase-Mediated Events Differentially Regulated by Endogenous Ras

1998 ◽  
Vol 18 (4) ◽  
pp. 1802-1811 ◽  
Author(s):  
David H. J. van Weering ◽  
Johan de Rooij ◽  
Barbara Marte ◽  
Julian Downward ◽  
Johannes L. Bos ◽  
...  
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Protein Kinase ◽  
Egf Receptor ◽  
Protein Kinase B ◽  
Ectopic Expression ◽  
Differential Sensitivity ◽  
Phosphorylated Proteins ◽  
Phosphoinositide 3 Kinase

ABSTRACT Regulation of phosphoinositide 3-kinase (PI 3-kinase) can occur by binding of the regulatory p85 subunit to tyrosine-phosphorylated proteins and by binding of the p110 catalytic subunit to activated Ras. However, the way in which these regulatory mechanisms act to regulate PI 3-kinase in vivo is unclear. Here we show that several growth factors (basic fibroblast growth factor [bFGF], platelet-derived growth factor [PDGF], and epidermal growth factor [EGF; to activate an EGF receptor-Ret chimeric receptor]) all activate PI 3-kinase in vivo in the neuroectoderm-derived cell line SKF5. However, these growth factors differ in their ability to activate PI 3-kinase-dependent signaling. PDGF and EGF(Ret) treatment induced PI 3-kinase-dependent lamellipodium formation and protein kinase B (PKB) activation. In contrast, bFGF did not induce lamellipodium formation but activated PKB, albeit to a small extent. PDGF and EGF(Ret) stimulation resulted in binding of p85 to tyrosine-phosphorylated proteins and strong Ras activation. bFGF, however, induced only strong activation of Ras. In addition, while RasAsn17 abolished bFGF activation of PKB, PDGF- and EGF(Ret)-induced PKB activation was only partially inhibited and lamellipodium formation was unaffected. Interestingly, in contrast to activation of only endogenous Ras (bFGF), ectopic expression of activated Ras did result in lamellipodium formation. From this we conclude that, in vivo, p85 and Ras synergize to activate PI 3-kinase and that strong activation of only endogenous Ras exerts a small effect on PI 3-kinase activity, sufficient for PKB activation but not lamellipodium formation. This differential sensitivity to PI 3-kinase activation could be explained by our finding that PKB activation and lamellipodium formation are independent PI 3-kinase-induced events.

Lupeol induces autophagy and apoptosis with reduced cancer stem-like properties in retinoblastoma via phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin inhibition

2021 ◽  
Author(s):  
Songtian Che ◽  
Shuai Wu ◽  
Peng Yu
Keyword(s):  
Protein Kinase ◽  
Cell Lines ◽  
Protein Kinase B ◽  
Mammalian Target Of Rapamycin ◽  
Inhibitory Effect ◽  
Target Of Rapamycin ◽  
Anticancer Effects ◽  
Retinoblastoma Cells ◽  
Phosphoinositide 3 Kinase

Abstract Objectives To evaluate the anticancer effects of lupeol in retinoblastoma cells. Methods WERI-Rb-1 and Y-79 cell lines were used to evaluate the anticancer effect of lupeol. After lupeol treatment, the viability, proliferation, apoptosis, cancer stem-like properties, autophagy and in vivo tumour xenograft formation were detected. Key findings In this study, lupeol decreased cell viability in both WERI-Rb-1 and Y-79 cell lines. Lupeol could also inhibit proliferation and induce apoptosis of RB cells, with increased Bax level and decreased Ki67, survivin and Bcl-2 levels. Furthermore, lupeol could suppress the spheroid formation and stem-like properties of RB cells. Moreover, LC3 II/LC3 I ratio and the levels of Beclin1 and ATG7 were increased after lupeol treatment, indicating that lupeol could induce autophagy in RB cells. Next, the inhibitory effect of lupeol on the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway was observed. In tumour-bearing mice, lupeol suppressed tumour growth, and this might relate to its role in cell apoptosis, autophagy and stem-like properties. Conclusions Lupeol suppressed proliferation and cancer stem-like properties, and promoted autophagy and apoptosis of RB cells by restraining the PI3K/AKT/mTOR pathway.

scholarly journals Identification of filamin C as a new physiological substrate of PKBα using KESTREL

2004 ◽  
Vol 384 (3) ◽  
pp. 489-494 ◽  
Author(s):  
James T. MURRAY ◽  
David G. CAMPBELL ◽  
Mark PEGGIE ◽  
Mora ALFONSO ◽  
Philip COHEN
Keyword(s):  
Protein Kinase ◽  
Cardiac Muscle ◽  
Mammalian Target Of Rapamycin ◽  
Specific Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Phosphoinositide 3 Kinase ◽  
Filamin C

We detected a protein in rabbit skeletal muscle extracts that was phosphorylated rapidly by PKBα (protein kinase Bα), but not by SGK1 (serum- and glucocorticoid-induced kinase 1), and identified it as the cytoskeletal protein FLNc (filamin C). PKBα phosphorylated FLNc at Ser2213in vitro, which lies in an insert not present in the FLNa and FLNb isoforms. Ser2213 became phosphorylated when C2C12 myoblasts were stimulated with insulin or epidermal growth factor, and phosphorylation was prevented by low concentrations of wortmannin, at which it is a relatively specific inhibitor of phosphoinositide 3-kinase. PD 184352 [an inhibitor of the classical MAPK (mitogen-activated protein kinase) cascade] and/or rapamycin [an inhibitor of mTOR (mammalian target of rapamycin)] had no effect. Insulin also induced the phosphorylation of FLNc at Ser2213 in cardiac muscle in vivo, but not in cardiac muscle that does not express PDK1 (3-phosphoinositide-dependent kinase 1), the upstream activator of PKB. These results identify the muscle-specific isoform FLNc as a new physiological substrate for PKB.

Baicalin Induces Apoptotic Death of Human Chondrosarcoma Cells through Mitochondrial Dysfunction and Downregulation of the PI3K/Akt/mTOR Pathway

Planta Medica ◽  
2018 ◽  
Vol 85 (05) ◽  
pp. 360-369 ◽  
Author(s):  
Minyu Zhu ◽  
Jinwei Ying ◽  
Chaowei Lin ◽  
Yu Wang ◽  
Kelun Huang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase B ◽  
Tumour Size ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Human Chondrosarcoma ◽  
Apoptotic Death ◽  
Phosphoinositide 3 Kinase

AbstractThe aim of the present study was to investigate the cytotoxic and antitumour effects of baicalin in human chondrosarcoma both in vivo and in vitro. We examined the effects of baicalin on the growth and apoptosis of human chondrosarcoma cells. Baicalin inhibited the growth of SW1353 and CH2879 cells in a dose- and time-dependent manner, but did not inhibit the growth of normal chondrocytes. Baicalin reduced tumour growth and induced apoptotic death in SW1353-transplanted nude mice without reducing their body weight. Further studies showed that baicalin reduced the mitochondrial membrane potential, upregulated the expression of Bax and cytoplasmic cytochrome c, downregulated the expression of Bcl-2 and mitochondrial cytochromes, and activated caspase-3 and caspase-9. Baicalin inhibited the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway by decreasing the expression of phosphorylated phosphoinositide 3-kinase, phosphorylated protein kinase B, and phosphorylated mammalian target of rapamycin both in vivo and in vitro. Moreover, the mice that received SC79 and baicalin exhibited a greater tumour size compared with the mice that received baicalin. The mice that received LY294002 and baicalin showed a smaller tumour size compared with the mice that received baicalin. In the in vitro study, SC79 and LY294002 affected the baicalin-induced cytotoxic effects on chondrosarcoma cells in the same manner. Our data suggest baicalin has therapeutic efficacy in human chondrosarcoma through the induction of apoptosis and inhibition of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway. Baicalin can be considered a potential therapeutic agent for treating chondrosarcomas.

Lupeol Inhibits Proliferation and Promotes Apoptosis of Ovarian Cancer Cells by Inactivating Phosphoinositide-3-Kinase/Protein Kinase B/ Mammalian Target of Rapamycin Pathway

2020 ◽  
Vol 19 (2) ◽  
pp. 206-210
Author(s):  
Feng Chen ◽  
Bei Zhang
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Protein Kinase ◽  
Cell Viability ◽  
Cancer Cells ◽  
Protein Kinase B ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Ovarian Cancer Cells ◽  
Phosphoinositide 3 Kinase

Lupeol exhibits multiple pharmacological activities including, anticancerous, anti-inflammatory, and antioxidant. The aim of this study was to explore the anticancerous activity of lupeol on ovarian cancer cells and examine its mechanism of action. To this end, increasing concentrations of lupeol on cell viability, cell cycle, and apoptosis in Caov-3 cells were evaluated. Lupeol inhibited cell viability, induced G1 phase arrest in cell cycle, increased cell apoptosis, and inhibited the ratio of phospho-Akt/protein kinase B and phospho-mammalian target of rapamycin/mammalian target of rapamycin. In conclusion, these data suggest that lupeol may play a therapeutic role in ovarian cancer.

Critical role for programmed death 1 signaling and protein kinase B in augmented regulatory T-cell induction in cord blood

2011 ◽  
Vol 128 (6) ◽  
pp. 1369-1371 ◽  
Author(s):  
Sytze de Roock ◽  
Sanne B.E.A. Hoeks ◽  
Linda Meurs ◽  
Anouk Steur ◽  
Maarten O. Hoekstra ◽  
...  
Keyword(s):  
T Cell ◽  
Protein Kinase ◽  
Cord Blood ◽  
Regulatory T Cell ◽  
Protein Kinase B ◽  
Critical Role ◽  
Programmed Death ◽  
Cell Induction ◽  
Programmed Death 1

scholarly journals Lovastatin inhibits the growth and survival pathway of phosphoinositide 3-kinase/protein kinase B in immortalized rat brain neuroblasts

2005 ◽  
Vol 94 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Maria Isabel Cerezo-Guisado ◽  
Luis Jesus Garcia-Marin ◽  
Maria Jesus Lorenzo ◽  
Maria Julia Bragado
Keyword(s):  
Protein Kinase ◽  
Rat Brain ◽  
Protein Kinase B ◽  
Growth And Survival ◽  
Survival Pathway ◽  
Phosphoinositide 3 Kinase
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